1. Field of the Invention
The present invention generally relates to a permanent magnet rotating electric machine and, more particularly, to a permanent magnet rotating electric machine to be mounted on a compressor of an air conditioner.
2. Description of the Related Art
Hitherto, such kinds of permanent magnet rotating electric machines have employed permanent magnets of various shapes. For example, Japanese Unexamined Patent Application Publication No. 6-339241 describes a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core, thereby enhancing an output of the rotating electric machine by utilizing reluctance torque.
The aforementioned conventional permanent magnet rotating electric machine comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core, thereby enhancing the efficiency of the rotating electric machine by effectively utilizing reluctance torque.
However, the conventional permanent magnet rotating electric machine has a drawback in that the adoption of the concentrated windings results in reduction in an effective range of induced voltages, and that when the rotating electric machine is driven by a position sensorless inverter in the case of 120 degree energization, a position sensor signal due to the induced voltage is not obtained and thus the rotating electric machine is out of working order.
Accordingly, an object of the present invention is to provide a permanent magnet rotating electric machine using a stator employing concentrated windings and a magnet-embedded rotor, which can be stably driven even when driven by a position sensorless inverter in the case of 120 degree energization.
To achieve the foregoing object, according to an aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, each pair of adjacent ones of permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a nearly V-shaped recess portion is formed between adjacent poles in outer circumferential surface portions of the rotor core.
Further, according to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a nearly V-shaped recess portion is formed between adjacent poles in outer circumferential surface portions of the rotor core. Furthermore, a plurality of slits radially extending in the rotor are formed in an outer circumferential portion, which is located outwardly from the permanent magnets, of the rotor core.
Moreover, according to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, a slit radially extending in the rotor is formed in a central portion of each of the teeth of the stator core. Further, each pair of adjacent ones of permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a nearly V-shaped recess portion is formed between adjacent poles in outer circumferential surface portions of the rotor core.
According to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, a slit radially extending in the rotor is formed in a central portion of each of the teeth of the stator core. Further, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a nearly V-shaped recess portion is formed between adjacent poles in outer circumferential surface portions of the rotor core. Furthermore, a plurality of slits radially extending in the rotor are formed in an outer circumferential portion, which is located outwardly from the permanent magnets, of the rotor core.
To achieve the foregoing object, according to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a plurality of nearly V-shaped recess portions, each of which is placed between adjacent poles of each pair, are formed in outer circumferential surface portions of the rotor core.
Further, according to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a plurality of nearly V-shaped recess portions, each of which is placed between adjacent poles, are formed in outer circumferential surface portions of the rotor core. Furthermore, a plurality of slits radially extending in the rotor are formed in an outer circumferential portion, which is located outwardly from the permanent magnets, of the rotor core.
Moreover, according to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a plurality of nearly L-shaped recess portion s, each of which is placed between adjacent poles of each pair, are formed in outer circumferential surface portions of the rotor core.
According to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Further, a plurality of nearly L-shaped recess portions, each of which is placed between adjacent poles, are formed in outer circumferential surface portions of the rotor core. Furthermore, a plurality of slits radially extending in the rotor are formed in an outer circumferential portion, which is located outwardly from the permanent magnets, of the rotor core.
To achieve the foregoing object, according to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, a slit radially extending in the rotor is formed in a central portion of each of the teeth of the stator core. Further, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a plurality of nearly V-shaped recess portions, each of which is placed between adjacent poles of each pair, are formed in outer circumferential surface portions of the rotor core.
Further, according to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, a slit radially extending in the rotor is formed in a central portion of each of the teeth of the stator core. Further, the each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a plurality of nearly V-shaped recess portions, each of which is placed between adjacent poles, are formed in outer circumferential surface portions of the rotor core. Furthermore, a plurality of slits radially extending in the rotor are formed in an outer circumferential portion, which is located outwardly from the permanent magnets, of the rotor core.
Moreover, according to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, a slit radially extending in the rotor is formed in a central portion of each of the teeth of the stator core. Further, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a plurality of nearly L-shaped recess portion s, each of which is placed between adjacent poles of each pair, are formed in outer circumferential surface portions of the rotor core.
According to another aspect of the present invention, there is provided a permanent magnet rotating electric machine that comprises a stator, into which concentratively wound armature windings are inserted in such a way as to surround a plurality of teeth formed in a stator core, and a rotor having permanent magnets accommodated into a plurality of permanent magnet inserting holes formed in a rotor core. In this machine, a slit radially extending in the rotor is formed in a central portion of each of the teeth of the stator core. Further, each pair of adjacent ones of the permanent magnets is arranged like a convex V or the permanent magnets are convex and U-shaped with respect to a rotor axis. Moreover, a plurality of nearly L-shaped recess portion s, each of which is placed between adjacent poles of each pair, are formed in outer circumferential surface portions of the rotor core. Furthermore, a plurality of slits radially extending in the rotor are formed in an outer circumferential portion, which is located outwardly from the permanent magnets, of the rotor core.
In the permanent magnet rotating electric machine of the present invention, a convex portion core may be placed between nearly V-shaped or L-shaped concave portions formed in outer circumferential surface portions of the rotor core. Moreover, the width of an innermost-circumference-side part of the convex portion core may be made to be larger than an outermost-circumference-side circumferential distance between the permanent magnet inserting holes.
Incidentally, let xcex82 denote an angle between segments respectively drawn from the rotor axis to both points of intersection of the outer circumferential surface of the rotor core 8 and the V-shaped or L-shaped recess portion. Further, let xcex84 designate a value obtained by dividing 360 (deg.) by the number of poles. In one of the aforementioned permanent magnet rotating electric machines, preferably, a ratio (xcex82/xcex84) is set so that 66.7%xe2x89xa6(xcex82/xcex84)xe2x89xa685.7%.
When the rotating electric machine is driven by using the position sensorless inverter in the case of 120 degree energization, a rotor position is detected by sensing an induced voltage in the rotating electric machine. That is, differently from a 120-degree energization section, an induced voltage appears between the terminals of the rotating electric machine in a 30-degree non-energization section. The rotor position is detected from a zerocross point thereof.
An armature current flows through the windings. Thus, it is necessary to perform commutation thereof in the 30 degree non-energization section. However, the concentrated windings have high inductance. Moreover, the range of induced voltages is narrow. Thus, the armature current cannot quickly be reduced.
As a countermeasure against this, it is considered that the inductance of the wirings is reduced.
However, the leakage inductance of the windings themselves are regulated owing to the structural conditions. Moreover, the magnitude thereof is low. Therefore, it is sufficient for reducing the inductance of the windings to reduce inductance called xe2x80x9cq-axis inductancexe2x80x9d, which is generated according to the coupling between the rotor core and the armature windings.
The present invention is based on this principle. The leakage magnetic flux of the permanent magnets is reduced by arranging the permanent magnets like convex Vs with respect to the rotor axis and by providing nearly V-shaped recess portions each of which is formed in the outer circumferential portion of the rotor core and between adjacent poles. Thus, torque due to magnetic flux generated by the permanent magnets is increased. Moreover, armature reaction magnetic flux produced by an armature current is reduced.
Thus, the q-axis inductance decreases. Furthermore, the armature current commutation is quickly achieved. Consequently, according to the present invention, there is provided a permanent magnet rotating electric machine that can stably be driven even when the electric machine is driven by the position sensorless inverter in the case of 120 degree energization.